REACTIONS OF CELL-BODIES OF DIFFLUGIA. 



27 



the usual thing which takes place, if the missing parts be not too 

 far removed. 



II. Is the Phenomenon a Process of Feeding? 



From the experiments described in the preceding section the 

 conclusion was drawn that if a fragment of protoplasm be severed 

 from a Difflugia, it is usually reappropriated. The question nat- 

 urally arises : Does the animal react to its fragment as a piece of 

 food, or do the two coalesce? If the fragment is taken up as food, 

 we would expect to see: (a) formation of a food vacuole and 

 enlargement at site of ingestion, (b) a similar reaction to frag- 

 ments from closely related forms, and (c) no sharp distinction as 

 to whether or not the fragment showed visible signs of life, such 

 as movement. 



(a) In some of these observations the animals were in such a 

 position at the time contact was made that it was impossible to see 

 what took place on account of the shell, but in the majority of 

 cases the view was unobstructed, so the entire process could be 

 witnessed. The usual reaction is approximately as follows : As the 

 advancing pseudopods of the cell-body near the fragment they 

 usually cease to become attached to the substratum, as in the ordi- 

 nary process of locomotion; thus- movement on the part of the 

 animal is slowed down. If at this time only one pseudopod is 

 extended, smaller secondary ones may be sent out near its base or 

 from the mouth of the shell. The primary pseudopod may make 

 direct contact with the fragment, or it may form a small cup into 

 which the fragment is fitted, or a niche may be formed by the 

 extrusion of one or more secondary pseudopods, and contact is 

 made in the niche thus formed. If there are two or more primary 

 pseudopods, they may encircle the fragment collectively, or only 

 one of them may take part in the reaction. When contact is made 

 there is ordinarily a disturbance of the protoplasmic surfaces, 

 which varies from a mild local shock to a violent contortion in- 

 volving the entire (visible) protoplasm. When the "contact 

 shock " is very great it is impossible to observe what becomes of 

 the fragment, but when it is slight the granular ectoplasm consti- 

 tuting the fragment can be seen streaming into the pseudopod and 



